A LCD (Liquid Crystal Display), as a platform and a carrier for information exchange, carries transmission of a large amount of information, performs a more and more important function under a social background of development and progress of the technology, and gradually becomes a key point of attention to people; and people have more and more expectations for new display modes and display effects. A polarizing plate, as an important component of the LCD, may absorb the light in a direction perpendicular to a polarizing axis, and only makes the light parallel with a polarizing axis direction pass through, thereby converting natural light into straight polarized light. However, more than 50% of light will be lost in this way, which greatly reduces the overall transmittance of the LCD. In addition, in the existing manufacturing process of the polarizer in mass production, a plurality of protection films and compensation films are needed, it will not only make the overall LCD be thick, but also raise the cost, and the difficulty of a manufacture procedure will also be increased, which all greatly limit the application of the LCD on energy conservation and portability.
Nanowire grids can transmit incident light of which a direction of the electric field is perpendicular to the wire grid direction, while reflect the light of which the direction of the electric field is parallel to the wire grid direction. Based on the working principle, the reflected light may be reused through the manners of adding anti-reflection films and the like, and thus, the ability to transmit the incident light of the nanowire grid polarizer is much greater than that of the conventional polarizer, the transmittance thereof may be up to more than 90%, and the contrast is also as high as 10000:1, which may greatly improve the transmittance and contrast of the LCD to meet the requirements of high transmittance and high contrast in the market.
The polarizing characteristics of the nanowire grids is decided by the material and the structure of the wire grid, and the structure parameters of the wire grid mainly include wire grid linewidth, wire grid depth, wire grid aspect ratio and so on. When the wire grid aspect ratio is small enough, and is far less than the wavelength range of the incident light, the wire grid can reflect almost all of the light of which the electric field vector component vibrates parallel to the wire grid, so that almost all of the light of which the electric field vector component is perpendicular to the wire grid is transmitted, and the smaller the wire grid aspect ratio is, the better the polarizing effect is. Therefore, how to obtain a sufficiently small wire grid aspect ratio and an appropriate depth-to-width ratio becomes the key to manufacturing the nanowire grids. The current main-stream manufacturing method mainly includes a dry-etching method and a wet-etching method; the principle of the dry-etching method is bombarding a wire grid material using high energy plasma, so that molecules of the material without PR protection escape, to produce an etching effect. The etching of this method is accurate and nanowire grids with a relatively large depth-to-width ratio can be obtained, but the energy consumption is too large and the equipment is expensive; and the wet-etching method uses chemical reagents to react with the wire grid material, reactants are dissolved in the chemical reagents, the part without PR protection are performed a reaction with the wire grid material in priority, and this method may greatly reduce energy consumption compared to the dry-etching method, but the etching positions thereof is isotropic and imprecise. Moreover, the reaction process is difficult to be controlled.